Abstract

Multiple-input multiple-output (MIMO) antenna systems have been shown to be able to substantially
increase date rate and improve reliability without extra spectrum and power resources. The increasing
popularity and enormous prospect of MIMO technology calls for a better understanding of the performance
of MIMO systems operating over practical environments. Motivated by this, this thesis provides
an analytical characterization of the capacity and performance of advanced MIMO antenna systems.
First, the ergodic capacity of MIMO Nakagami-m fading channels is investigated. A unified way of
deriving ergodic capacity bounds is developed under the majorization theory framework. The key idea is
to study the ergodic capacity through the distribution of the diagonal elements of the quadratic channel
HHy which is relatively easy to handle, avoiding the need of the eigenvalue distribution of the channel
matrix which is extremely difficult to obtain. The proposed method is first applied on the conventional
point-to-point MIMO systems under Nakagami-m fading, and later extended to the more general distributed
MIMO systems.
Second, the ergodic capacity of MIMO multi-keyhole and MIMO amplify-and-forward (AF) dual-hop
systems is studied. A set of new statistical properties involving product of random complex Gaussian
matrix, i.e., probability density function (p.d.f.) of an unordered eigenvalue, p.d.f. of the maximum
eigenvalue, expected determinant and log-determinant, is derived. Based on these, analytical closedform
expressions for the ergodic capacity of the systems are obtained and the connection between the
product channels and conventional point-to-point MIMO channels is also revealed.
Finally, the effect of co-channel interference is investigated. First, the performance of optimum combining
(OC) systems operating in Rayleigh-product channels is analyzed based on novel closed-form
expression of the cumulative distribution function (c.d.f.) of the maximum eigenvalue of the resultant
channel matrix. Then, for MIMO Rician channels and MIMO Rayleigh-product channels, the ergodic capacity
at low signal-to-noise ratio (SNR) regime is studied, and the impact of various system parameters,
such as transmit and receive antenna number, Rician factor, channel mean matrix and interference-tonoise-
ratio, is examined.